1. Field of the Invention
The present invention relates to a drive for adjusting parts of seating and reclining furniture, and more particularly to a drive applicable to a chair and sofa.
2. Related Art
A drive of this kind is known from DE-GM 89 03 603, in which a mechanism, consisting of a gear connected to a spindle and a worm engaging the gear, is arranged inside a housing. The worm is driven by an electric motor fastened to a side surface of the housing. A nut, on which a lifting tube capable of moving in a lifting tube receiving device is fastened, is guided in a non-twisting manner on the spindle within the lifting tube receiving device protruding from the housing. The lifting tube can be easily adjusted if this drive is fixed in a pivoting manner via the receiving device on the housing and the lifting tube is coupled with an adjuster for slatted bases.
Such a drive is particularly disadvantageous in that, its total length is determined by a necessary minimum length for guiding the lifting tube within the lifting tube receiving device plus a lifting path of the lifting tube. This minimum length is necessary in order to reliably prevent the lifting tube from bending over a long travel paths. This means that it is necessary to simultaneously prolong the lifting tube receiving device while increasing the stroke length of the lifting tube. Therefore, it is necessary to manufacture housings with different lengths of lifting tube receiving device within certain limits, and as a result, the manufacturing of the drives becomes considerably expensive.
Furthermore, such drive cannot be used in constricted spaces unobtrusively, for example, in adjustable seating and reclining furniture.
Moreover, an adjuster has been disclosed in DE 37 34 922 A1, which is designed to be adjustable in a longitudinal direction on a special section tube by means of a nut/spindle mechanism. The nut part located within the special section tube is designed in one piece, including a sliding shell that partially surrounds the special section tube and strips guided in grooves within the special section tube. A web that reaches through the groove within the special section tube and connects these parts is provided between the nut and the sliding shell. As the sliding shell only partially surrounds the special section tube, an additional sliding support is provided, and the sliding shell and the sliding support are screwed together. A large number of individual parts definitely require considerable efforts during assembling, and meanwhile result in an increased cost.